What is the sum of 69, 90, 21, 57, 43, 99, 79, and 80? Before you even begin to think about picking up a calculator to come up with the answer, this bunch of girls will have it ready for you, in less than six seconds. Watching them come up with super quick answers in this video is amazing. They utilise advanced abacus – an ancient calculation tool, and mental arithmetic techniques to solve complex arithmetic calculations within seconds by flicking their fingers. And they are taught to do so by using their fingers to keep track of long series of numbers to solve calculations like addition, subtraction and multiplication with high accuracy.

Abacus is a global technique used in preschools and elementary schools to teach math. It is one of the fastest ways of doing calculations especially when it comes to large numbers.

The use of this technique has spread among many students in India and this is an example of one such group.